1917] DISEASES OF PLANTS. 153 



The effect of asphyxiating' gases on grapevines at the battle front, P. 

 ViALA iCompt. Rend. Acad. Agr. France, 2 (1916), No. 20, pp. 558-561; Rev. 

 Vit., U {1916), No. 1146, pp. 424, 425).— An account is given of the effects upon 

 vegetation, particularlj^ upon grapevines, of exposure to tlie fumes released by 

 the explosion of aeroplane bombs dropped in raids during the latter part of 

 April, 1916. 



Severe injury was caused, which, it was found, could be duplicated by sub- 

 jecting the vines to chlorin fumes or by sprinkling them with Javelle water. 

 In case of outdoor plants on dry areas, discoloration was not so evident as 

 wliere dew was present, but the growth was temporarily checked after ab- 

 sorbing the injurious gases. Injury to the other plants varied with the stage 

 of their vegetative advancement. Rye and other cereals were affected. 



The effects of asphyxiating gas on vines, A. Cokdonnier and RicHEZ-PiiCHON 

 (Rev. Vit., 44 {1916), No. II4S, pp. 459-461) .—This contains a few particulars, 

 in addition to those reported above by Viala, of observations made on forms 

 of injury to plants by fumes from aeroplane bombs. 



Effects of gases from aeroplane bombs, A. Cokdonnier (Bui. Sac. Path. 

 Vcg. France, 3 {1916), No. 1, pp. 32, 33). — This is a brief account of the occur- 

 rences and results above noted. 



Citrus blast, a new disease in California, J. E. Coit (Univ. Cat. Jour. Agr., 

 S (1916), No. 6, pp. 23^, 235, figs. 2). — A brief account is given of a new citrus 

 disease which was first observed by the author in the spring of 1914 on an 

 old seedling orange tree near Oroville, Cal. Later in the same summer, the 

 disease was found in a number of commercial orchards in the northern districts 

 of that State. 



The disease is characterized by an apparent infection which takes place 

 nearly always at the joint between the petiole or leaf stalk and the leaf blade. 

 The leaf blade soon dies and the disease progresses downward to the twig, 

 involving the bark and killing it in a circular area from i to i in. in diameter. 

 When the twigs are small, girdling often results and the twig dies back to the 

 point of infection. Large twigs and limbs seem to have a certain degree of 

 resistance, the disease being confined to new growth and limbs not over 1 in. 

 in diameter. Badly infected trees are said to be filled with dead brush from 

 girdled twigs, and the dead twigs and leaves soon become covered with fungi. 

 The disease does its chief damage by killing the fruiting brush and greatly re- 

 ducing tlie bearing area of the tree. 



As a result of preliminary investigations, citrus blast is believed to be due 

 to bacteria. 



Citrus blast, a new disease, R. W. Hodgson (Pacific Rural Press, 92 (1916), 

 No. 6, p. 124). — An account is given of investigations carried on in 1915 on the 

 newly recognized bacterial disease of citrus occurring in northern California, 

 which, according to the author, was first observed in 1912, 



Infection is apparently confined to the new spring growth and occurs chiefly 

 at the junction of the petiole and blade of the leaf. It also occurs at the tips 

 of the very young leaves and tender shoots. When once established, the disease 

 is said to progress rapidly down the shoot toward the older wood, but only 

 the new tender growth is affected. Young shoots are often killed back to the 

 older wood, including a portion of the bark about the base of the infected 

 shoots, and it is not uncommon to find branches several feet long with every 

 node infected. Upon infection the leaves are said to turn pale yellow, then 

 to darken in spots and wilt, and later to shrivel and dry, though still hanging 

 to the shoot. 



The disease appears to spread with remarkable rapidity, only a few days of 

 favorable weather conditions being required for serious damage. As the dry 



